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Utility Bowl Finish Choice

Discussion in 'Woodturning Discussion Forum' started by William Rogers, Nov 21, 2017.

  1. William Rogers

    William Rogers

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    i have only done a few bowls. Seems there a lot of choices on finish. I'm sure wood choice plays a part. Most of my bowls will be cherry, walnut, maple, ash, and elm. Woods I have locally. Here is what I have or considered. What finish do you use and why?

    1. Walnut Oil. I have read mixed reviews about using Mahoney oil in regard to drying. I have some, but somewhat hesitant in using this. A black light is recommended to assist in drying.

    2. Danish Oil (Watco). I haven't used this on bowls, but seems it would be reasonable.

    3. WOP. Doesn't seem to be the best choice for a utility bowl. Does anyone use this for bowls

    3. Lacquer. Same as WOP.

    4. Salad Bowl Finish. I have use this and also the Watco brand called Butchr Block Finish. Works well.

    5. Mineral oil (with or without bees wax). I use this on my butcher blocks, but haven't used on a bowl.

    6. Boiled Linseed oil. Never used as concerned if it would go rancid.

    7. What else is there?

    If I can get over my fears I will try the walnut oil on my next cherry bowl. So far I seem to like the Watco butcher block Finish, but a little costly. I don't buff or wax after applying the finish.
     
  2. Derek Lane

    Derek Lane

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    I tend to keep clear of oils with nuts in them especially if selling bowls never know what allergies people have I tend to stick with proven food safe oils for those that will be in contact with food stuff
     
  3. Hy Tran

    Hy Tran

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    Based on the title of your post, I'm assuming you're looking for a finish that would be used for a food-containing bowl. The bowl would see frequent use and frequent cleaning (sponge/paper towel, warm soapy water & rinse, air dry).

    Based on Bob Flexner's book, all finishes, once fully cured, are food safe--the volatiles have volatilized, but I'd take that advice with a grain of salt...

    Cleaning and/or use of serving utensils will almost always wear finishes a bit. One question is how many cleanings before the finish is gone. Some folks don't bother finishing their utility bowls (with caveats added below).

    I'll start backwards:

    7: Epoxy resin, such as the System Three epoxies. About the only finish that will resist alcohol (e.g. if you're making a wood goblet for consuming distilled spirits). If you only rinse out the distilled spirits, I would imagine this would last practically forever. Difficult to apply in even coats, can sensitize the skin of the person who's applying the epoxy. (Not a sensitizer when fully cured).

    6.5 Shellac(s). Definitely food safe ("GRAS" according to the FDA, used as a coating for medical pills, and some hard candies). Will eventually wear away under use, not really waterproof.

    6.3 Tung oil (real tung oil, not "tung oil finish.") A polymerizing vegetable-derived oil. Thin coats, lots of time spent, not really waterproof.

    6. BLO: Does not turn rancid--"Boiled" is a euphemism for metal additives such as Zinc that make the linseed oil polymerize faster. Thin films polymerize when in contact with oxidizers (such as air!). Multiple thin coatings, etc. Will eventually wear away, not really waterproof. There are a number of vegetable oils that polymerize when in contact with air; linseed oil, flaxseed (same thing, but if you buy flaxseed oil at the health food store, you know it's edible and contains no metal salts to accelerate polymerization).

    5. Mineral oil will not polymerize. It repels water, but is not waterproof. It will want to be replenished periodically.

    4. Salad Bowl Finish (such as General Finishes SBF) is basically a polyurethane, similar chemistry to the wipe-on-poly's. It's a film finish that polymerizes or cross-links when the solvent evaporates (or possibly on contact with air). Water resistant, but not waterproof, unless it's applied in numbers of layers that are ridiculously thick.

    3. Lacquer: It's actually more similar to shellac than wipe-on poly. It's a resin-in-solution (the original lacquers). Modern lacquers are nitrocellulose polymers rather than tree resins, but again, they are in solution, and when the solvent evaporates, they bond through mechanical contact and Van Der Waals forces. Lacquers are generally more durable than shellacs. Not really waterproof.

    3. WOP-wipe-on-poly is just a viscosity/surface-tension-modified polyurethane finish. Upon evaporation of the solvent (and possibly exposure to air), the molecules cross-link & polymerize to form a film. Not waterproof.

    2. Danish oil. This is typically boiled linseed oil that's been pre-diluted with solvents such as mineral spirits, to make for easier and faster application. See BLO comments for water resistance.

    1. Walnut oils. This is a polymerizing vegetable-derived oil. Mahoney's (and Dr Woodshop's) assert that they have a process that removes the glycoproteins from the oil. Allergies are based on the glycoproteins and not the fatty acid chains in the oil. Applying in thin layers (and wiping off excess), and allowing each layer to polymerize in air would have similar cosmetic results as Danish oil or BLO. Again, see comments for water resistance.

    Buffing with Carnauba and/or bees wax: Carnauba and bee waxes are edible (but not the solvent carriers...). Does not make for a particularly durable or waterproof finish, but the buffing process puts a nice soft sheen on the surface.

    If you weigh cosmetics and convenience: For personal use, I'd do multiple layers of walnut oil (I'm not allergic, but theoretically, Mahoney's has had the glycoproteins removed), and do a final wax buff. I'd occasionally do a re-wipe of the insides with mineral oil (butcher block oil).
     
  4. hockenbery

    hockenbery AAW Advisor Staff Member

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    I use Waterlox on many bowls. It is similar to watco and I sometimes use watco for a first coat the waterlox.
    Usual three coats works to a not too shiny durable finish. One we have used as a fruit bowl looks great after 19years of service.
    In other uses it will last a while with abrasions from utensils, salt etc.
    Maybe year maybe days depending upon the intensity of the abrasions.
    And then it is usually the inside. I suggest that customers wipe the inside with mineral oil or walnut oil when the surfaces gets scratched up.
     
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  5. robo hippy

    robo hippy

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    I use the Doctor's Woodshop walnut oil. The bowl finish grades of walnut oil are different than the salad oils you get in the grocery store. I believe it is a heat treatment process which breaks down the nut proteins, which people are allergic to. Over heated or processed walnut oil will not cure.

    I don't use any solvent based finishes on my bowls. Ran into some one at a show who was sensitive to tolulene which is a common solvent for some finishes and she commented that it doesn't all go away. If I can't eat it out of the can, no matter what it tastes like, I don't really want it on my bowl. Mineral oil makes it look wet for a short time but doesn't really do anything. Bees wax is too soft to be of any real value. Carnuba is much harder. The Doctor's mix has the carnuba 'micro aggregated' so it flows without heat or solvents.

    robo hippy
     
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  6. tdrice

    tdrice

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    I finish the outside with wipe on poly, several coats. on the inside I use walnut oil unless the customer is concerned about allergies, (I always tell the customer about it.) in which case I use pharmaceutical grade mineral oil. In either case I include a small bottle of the oil and urge the buyer to re-oil when the finish looks dull.
     
  7. William Rogers

    William Rogers

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    I'm going to give the Mahoneys oil a shot. I don't do custom bowls like tdrice. Reed, do you tell your customers you use walnut oil?
     
  8. Tom Albrecht

    Tom Albrecht

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  9. egsiegel

    egsiegel

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    I have stopped using WOP, Watco, and BLO (all work well depending on what look you want).
    I am now using "wood butter"...1 part beeswax dissolved in 4 parts Mineral oil. I wipe it on with the lathe running and get a nice finish where I can actually "feel" the wood...no plasticy finish.
    It is fast and easy, food safe, and cheap. It can be refreshed easily. So far, I'm happy with it.
     
  10. robo hippy

    robo hippy

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    I have a care card, and more detailed instructions on my web site, but I always tell the customer that I use walnut oil. If they have allergy concerns, I tell them what the maker tells me. I have sold maybe 2 naked bowls during my career.

    robo hippy
     
  11. Dennis J Gooding

    Dennis J Gooding

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    I do not turn bowls for sale, but for my own use and for gifts, I use walnut oil. I suspect that the risk of allergic reaction is extremely low. As Hy pointed out, the allergens are associated with the proteins in the nut not the extracted oil. Furthermore, most of what is retained in the oil will be entrapped when the oil polymerizes into a solid. The remainder, if water soluble or dislodgeable as particles and hence able to be transferred to a diner should disappear in the first washing or so.

    Regarding curing of walnut oil: A couple of years ago, I ran some experiments on drying time using three store brands of walnut oil plus Mahoney's. I saturated small pieces of paper towel with each of the candidate oils and measured the drying times. I chose paper rather than wood for the test because it is difficult to tell if the oil has hardened in a piece of wood, whereas the paper becomes rigid. Both are primarily cellulose. In the first experiment, I hung the strips in a dark closet. After about 3 months, all of the strips were still wet and limp. I repeated the experiments with the strips hung in a south--facing window. In three days all of the strips were dry and crisp. Although I did not check the drying process frequently, I did not notice any significant difference in the drying rates of the various oils. An interesting follow-up experiment would have been to expose strips to artificial indoor lighting to see how long it takes for them to harden.
     
  12. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Dennis, the results of your experiment are very interesting and help to confirm my suspicions. I've been using La Tourangelle Roasted Walnut Oil for several years, but early last year decided to buy a bottle of Mahoney's Walnut Oil to make a comparison. They both smelled the same and had the same color and the viscosities appeared to be the same. Your paper towel test was much more clever than my test on a maple turning blank. I applied the two oils to the blank with paper towels and left the space between them unfinished to show the color change. As far as I could determine both dried in the same length of time and both smelled the same while drying.

    Here is a snapshot of how the two finishes look today. The surface of the blank had been planed with what must have been dull blades and I didn't bother sanding the surface smooth before applying the finishes. I think that I should continue applying additional coats of walnut oil just to see what happens.

    image.jpeg

    Mahoney's Walnut Oil uses the term "heat treated" and La Tourangelle uses the word "roasted," same thing depending upon your audience ... the end result is partial polymerization of the alpha linolenic acid which is about 10% of walnut oil. Linseed oil uses transition metal catalysts to accelerate polymerization of the alpha linolenic acid.
     
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  13. odie

    odie

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    Although I did a little experimenting in the beginning, I've pretty much stayed with Watco danish oil natural for the better part of the past three decades. Some on this forum will remember when I was asking a lot of questions about non-toxic finishes a few years back......but, I'm still using the WDO, even for my salad bowls. The trick is to "fully cure", and my salad bowls usually set for a couple of weeks after application, and I finish it off with a non-toxic wax coating. The WDO becomes non-toxic after fully curing.

    The main reason I have stayed with the Watco danish oil natural for food safe bowls, is because it also seals the pores in the wood. For food use, I believe this is an advantage, as nut oils wouldn't seal the pores as well. As I mentioned, take care to make sure fully curing the WDO is observed.....time is your friend!

    For several years now, I've been using "lemon oil wax", for a top coat.....available from CSUSA. I do not apply the LOW until after the salad bowl is sold......so, that it's a freshly waxed surface when they open the package. The LOW will tend to dull, given some time.

    https://www.woodturnerscatalog.com/p/41/2249/Artisan-Lemon-Oil-Wax

    The lemon oil wax isn't permanent, but I suggest my food bowl customers to wipe clean with damp rag, and apply a coat of mineral oil to preserve.

    For decorative bowls, the WDO is also a great finish......but, I should mention that it doesn't hide flaws created by substandard tool usage and sanding very well. The trick is to develop and refine your "on the lathe" techniques so that the flaws aren't there! (I know that's a tall order for some new turners.....but, it should be every turner's goal.) For decorative bowls, I switched to the Beall method a few years ago......that was a great improvement, but not recommended for food use.....mainly because of the EEE, and white diamond steps. The Carnauba wax is non-toxic, however. Up until the time I switched to the Beall method, I was using the Liberon Black Bison Wax.....which was good, but the Beall method is much better! (The Beall 3-step method has a learning curve, and will grab your bowl, flinging it across the shop......until you get the hang of it!) ;)

    -----odie-----
     
    Last edited: Nov 22, 2017
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  14. Dennis J Gooding

    Dennis J Gooding

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    Bill, La Tourangelle was one of the three off the shelf oils I tested.
     
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  15. robo hippy

    robo hippy

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    I used to use the Deft Oil on my furniture pieces. Then I switched to Deft because the Deft had a little poly in it. The Deft would 'dry' out and look dull in fairly short order. I would wet sand 3 or so coats on each piece. Not sure if the Deft is still around. I know they were sold a while back, and I could still order it through a local store, but they didn't carry it in stock any more...

    robo hippy
     
  16. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I'm confused. :confused:
     
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  17. Emiliano Achaval

    Emiliano Achaval

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    Me too, lol
     
  18. robo hippy

    robo hippy

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    Oops, I meant Watco Danish oil had no poly in it..... The Deft did.... Brain flatulation....

    robo hippy
     
  19. n7bsn

    n7bsn

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    My wife is (highly) allergic to walnuts, but she use's walnut oil (Mahoney's & Doctors) on her items with zero issues

    We avoid mineral oil simply because it evaporates. It provides no protection after that.
     
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